Prevention of the angiopathic consequences of protracted diabetes remains a primary therapeutic goal. One possible approach to this problem is to provide physiologic glucose homeostasis in the diabetic patient by intermittent or continuous insulin infusion from an artificial beta cell. While development of devices of this type suitable for clinical use is still some years away, we have developed a totally implantable insulin delivery system capable of intravenous delivery at two flow rates. Using this system we have demonstrated that near normal glucose tolerance tests and 16-hour glucose profiles can be achieved. Our objective is to compare the effect of blood glucose control by pump-infused insulin versus prospective minimal and good control by conventional insulin injection on the development of diabetic nephropathy. We have chosen the dog for this study since this pump which is designed for future clinical use is too large for use in the rat. We hope to reduce the time required for lesions to develop by performing unilateral nephrectomies on these dogs, a technique used successfully in the experimentally diabetic rat.